The present invention relates to slide mounter for preparing photographic slides for use with a slide projector. More specifically, the present invention relates to an apparatus for advancing a photographic film web for operation in semi-automatic or automatic slide mounters.
In semi-automatic and automatic slide mounters, individual film transparencies are severed from a photographic film web and inserted into a slide mount. The film transparencies are severed from the photographic film web by a knife assembly formed of upper and lower blades designed to operate between a closed cutting position and an opened receiving position. Typically, the film web is mechanically advanced across the knife blades from a supported position along a film track while the knife assembly is in the opened receiving position. When a trailing edge of a leading film transparency of the film web is properly positioned, the upper and lower blades are closed together to sever the film transparency from the film web. The severed film transparency is then inserted into a slide mount to complete the photographic slide.
The design of the knife assembly defines a support gap across which the film must be advanced to align the trailing edge of the leading film transparency with the upper and lower knife blades. In typical past applications, the film has been advanced along a roller slide support to advance the film transparency across the support gap of the knife assembly for operation. However, in such applications, the leading edge of the film is advanced forward across the support gap without support. Since the leading edge is advanced unsupported it is often difficult to guide the film transparency across the support gap of the knife assembly. This is particularly so since the film transparency has a tendency to curl because the film web is originally wrapped around a storage reel. Thus, when advanced unsupported, the film transparency has a tendency to want to return to its originally wrapped position. Also, the emulsion with which the photographic film is coated causes the film transparency to curl along the direction of advancement of the film transparency across the support gap of the knife assembly. The propensity of the film transparency to curl is further aggravated by the advancement force which is used to advance the film for operation.
Thus, there has been a continuing need to develop an apparatus which will consistently advance, without difficulty, the film web across the knife support gap to align the trailing edge of a leading film transparency with the upper and lower blades of the knife assembly. That is, there has been a continuing need to develop a mechanism for operation with an automatic or semi-automatic slide mounter that will advance the film and which will not cause the film to curl along the direction of advancement and thus interrupt the continuous operation of the slide mounter.